The present invention relates to a bag mounted on casters, and in particular, to a bag having a vertically extensible handle. The term "bag", in the present invention, is used broadly to refer to suit-cases and attache-cases.
Bags provided with casters and a freely extensible handle, have already been developed and widely used. Many types of bags having this structure can be boarded or stored in the passenger cabin of airplanes. For example, known bags having the above-described structure are disclosed in U.S. Pat. No. 4,995,487; Japanese Patent Publication No. 4-76686, issued Dec. 4, 1992; Japanese Non-examined utility Model Publication No. 57-179824, issued Nov. 15, 1982; and Japanese Non-examined utility Model Publication No. 63-131634, issued Aug. 29, 1988. The bags described in these publications are provided with two casters mounted on one side of a bottom face of the bag, as shown in FIG. 1 of the present invention. Short legs 2 are fixed on an opposite side of the bottom face of the bag, relative to the two casters. The casters 1 and the legs 2 contact the floor when the bag is in a vertical position. In the vertical position, the bag can stand upright without moving because the legs 2 are in contact with the floor. Further, the extensible handle 3 is provided at an upper face of the bag so as to allow the bag to be pulled. The casters 1 are mounted on the same side of the bag as the handle because the bag is pulled while in a slanted or tilted orientation.
As shown in FIG. 1, the prior art bag can be moved when it is tilted and pulled by the handle 3. When the bag is tilted, only the casters 1 are in contact with the floor. When the handle 3 is pulled in the tilted orientation, the casters 1 turn in order to facilitate movement of the bag. However, bags moving in this fashion sometimes do not allow the casters 1 to be used in narrow places like the interior of planes or in crowded areas. When the bag is moved using the casters 1, the widest dimension of the bag is perpendicular to the movement direction, and thus the bag cannot be moved freely in the aisles of an airplane cabin or in crowded areas.
The bag mounted on casters allows large, heavy bags to be easily moved. This is because, even if the bag is heavy, it is easily pulled along on the rolling casters. In order to solve the drawbacks associated with prior art bags, the inventor of the present invention previously developed the bag shown in the FIG. 2. The bag shown in FIG. 2 has casters 21 fixed at a bottom face 24A of bag body 24. The casters 21 are mounted at the four corners of the bottom face in order to allow the bag body 24 to be self-standing while in an upright position. A grip 27 of the handle 23 is located at the center of the upper face of the bag body 24. Also, as opposed to bag shown in the FIG. 1, the bag of FIG. 2 does not have to be tilted in order to move the bag. The bag is moved in the direction shown by the arrow of the FIG. 2 while remaining in an upright vertical position. Therefore, when the bag is moved in the direction shown by the arrow, the widest dimension of the bag is parallel to the movement direction. For this reason, the bag has the advantage that it can be conveniently moved in an airplane cabins or in crowded areas. Further, by using freely spinning casters which allow movement in any direction, the bag can be freely moved in any direction while in an upright position. Note that the upright bag does not transmit the weight of the bag to the handle 23. Therefore, even a fairly heavy bag can be easily pushed and moved.
The bag of FIG. 2, uses four casters 21 which allows easy movement thereof. However, a guide pipe, which connects the handle 23 to the bag body 24, causes a reduction in the interior storage capacity of the bag body 24. The reduction in storage capacity becomes an even greater problem as the bag body 24 gets thinner. This is because the guide pipes generally occupy the same volume in the bag body 24, regardless of the thickness of the bag body 24. In particular, the guide pipes have to be mounted at the center of the bag body 24 in order to allow the bag to be pushed with good balance, and this will limit the thickness of an item which can be stored inside the bag body 24. Items of almost the same thickness as the bag body can be stored inside a bag body without guide pipes. In comparison, bags with guide pipes at the center of the bag body permit the storage of items which are less than half the thickness of the bag body due to the volume of interior space occupied by the guide pipes.
Further, the bag supported on casters not only allows movement of the bag regardless of the weight of the items stored inside of the bag, but also allows easy movement thereof because it can be used as a walking stick. In the bag shown in FIG. 2, the vertical rods 26 are stopped by means of stopper in an extended position, thereby setting the height of the grip 27 at 80 to 90 cm which allows the handle to be used as a walking stick. However, it is necessary to reinforce the bottom face of the bag so as to allow it to be used as a stick. A bending force is applied to the bottom face of the bag when the grip is pushed. Therefore, in order to avoid distortion of the bottom face, it is necessary to strongly reinforce the bottom face of the bag. The bag becomes heavier when reinforced, and for example it cannot be easily moved when lifted and carried on stairs.